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Title: Impact of the Normalization Condition and Model Information on Evaluated Prompt Fission Neutron Spectra and Associated Uncertainties

Abstract

Low evaluated uncertainties compared to experimental information and a strong model impact were observed in some prompt fission neutron spectrum (PFNS) evaluations that include mean values and covariances stemming from a rigid model. Here, we show by studying the (PU)-P-239 PFNS ENDF/B-VII.1 evaluation via generalized least-squares analyses that strong model correlations in combination with the normalization condition on the estimated PFNS and its covariances result in surprisingly low evaluated uncertainties. Furthermore, the model changes the evaluated results by > 1 sigma of combined experimental uncertainties near the average outgoing neutron energy (similar to 2 MeV). We show both analytically and by means of representative numerical examples that the normalization condition on the spectrum and its covariances naturally leads to uncertainties reduced by a fully positively correlated scaling uncertainty

Authors:
 [1];  [2];  [3];  [4];  [1]
  1. Los Alamos National Laboratory, Theoretical Division T-2 Nuclear and Particle Physics, Astrophysics and Cosmology Los Alamos, New Mexico
  2. International Atomic Energy Agency, Nuclear Data Section Vienna, Austria
  3. Argonne National Laboratory, Nuclear Engineering Division Argonne, Illinois
  4. Los Alamos National Laboratory, CCS-6: Statistical Sciences Los Alamos, New Mexico
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science - Office of Nuclear Physics; USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1391741
DOE Contract Number:
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nuclear Science and Engineering; Journal Volume: 179; Journal Issue: 4
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS

Citation Formats

Neudecker, D., Capote, R., Smith, D. L., Burr, T., and Talou, P.. Impact of the Normalization Condition and Model Information on Evaluated Prompt Fission Neutron Spectra and Associated Uncertainties. United States: N. p., 2015. Web. doi:10.13182/NSE14-6.
Neudecker, D., Capote, R., Smith, D. L., Burr, T., & Talou, P.. Impact of the Normalization Condition and Model Information on Evaluated Prompt Fission Neutron Spectra and Associated Uncertainties. United States. doi:10.13182/NSE14-6.
Neudecker, D., Capote, R., Smith, D. L., Burr, T., and Talou, P.. Wed . "Impact of the Normalization Condition and Model Information on Evaluated Prompt Fission Neutron Spectra and Associated Uncertainties". United States. doi:10.13182/NSE14-6.
@article{osti_1391741,
title = {Impact of the Normalization Condition and Model Information on Evaluated Prompt Fission Neutron Spectra and Associated Uncertainties},
author = {Neudecker, D. and Capote, R. and Smith, D. L. and Burr, T. and Talou, P.},
abstractNote = {Low evaluated uncertainties compared to experimental information and a strong model impact were observed in some prompt fission neutron spectrum (PFNS) evaluations that include mean values and covariances stemming from a rigid model. Here, we show by studying the (PU)-P-239 PFNS ENDF/B-VII.1 evaluation via generalized least-squares analyses that strong model correlations in combination with the normalization condition on the estimated PFNS and its covariances result in surprisingly low evaluated uncertainties. Furthermore, the model changes the evaluated results by > 1 sigma of combined experimental uncertainties near the average outgoing neutron energy (similar to 2 MeV). We show both analytically and by means of representative numerical examples that the normalization condition on the spectrum and its covariances naturally leads to uncertainties reduced by a fully positively correlated scaling uncertainty},
doi = {10.13182/NSE14-6},
journal = {Nuclear Science and Engineering},
number = 4,
volume = 179,
place = {United States},
year = {Wed Apr 01 00:00:00 EDT 2015},
month = {Wed Apr 01 00:00:00 EDT 2015}
}